Indirect domestic water-heating system



Jgly 6, 1926.

1,591,647 C. SMiTH INDIRECT DOMESTIC WATER HEATING SYSTEM Filed Jan. 191920 2 SheetsSheet 1 i il WI n M W W July 6 1926. 1,591,645? c. SMITHINDIRECT DOMESTIC WATER HEATING SYSTEM Filed Jan. 19, 1920 2Sheets-Sheet 2 Patented July 6, 1926.

UNlTED eras CHETWOOD SMITE, F WQRCESTER, MASSACHUSETTS.

INDIRECT DOMESTIC WATER-HEATING SYSTEM.

Application filed January 19, 1920. Serial No. 352,508.

The present invention relates to means for heating Water for domesticuse; and by domestic use I mean use for washing and analogous purposesin dwellings and buildings of all sorts occupied by human belngs, wherehot Water is needed for any other purpose than as the circulating fluidin a heating system. More particularly my object is to use the heater orfurnace of a hot Water heating system as the generator by which tosupply heat for heating water for domesti purposes; and further to dothis in a manner and by means which supplies sullicient heat in mildweather when a slow fire is maintained in the furnace. and pre ventsoverheating and possible damage to the'apparatus and danger to occupantsof: the building, when the fire is made more brisk in cold weather. Thisobject is ac complished by heating the domestic water in an indirectheater through thermal contact with circulating water which is heated inthe furnace, and by providing means to permit flow of such circulatingwater into the water heating system when the tempera ture of thedomestic water has been raised. high endugh. The meansfor accomplishingsaid object, and the principles which such means embody, constitute thepresent invention and are fully described and explained in the followingspecification with reference to the drawings furnished therewith.

In the drawings, Figure l is a diagram partly .in elevation. and partlyin section of a heating system containing this invention.

Figures 2 and 3 are detail'views of a heating coil used in connectionwith the apparatus shown in Figure 1,

Figure 4 is a diagram of a modified form of phe invention embodying thesame prin= c1 es,

Like reference characters designate the same parts in all the figures.

Referring first to Figure 1, 5 represents the furnace or a hot waterheating system, which may be of any type or make. This figure representsthe back of the furnace and shows a part broken away at one side;Referring to the broken away part, 6 represents the interior or fire potor the space of the furnace; 7 represents a water leg surrounding thefire space; 8 and 9 represent water sections at the top of the furnaceand, with the water leg '3, comprises what may be called the water spaceof the furnace; and 11, 11 and 12, represent the circulating pipes ofthe heating system, by which respectively hot water is carried away fromthe upper section to the radiators and spent water is returned to thelower part of the water leg.

13 represents a water heater by which water for domestic purposes, thatis, for washing or any other purpose which requires the water to bedrawn 0d from the pipes containing it, is heated. This heater comprisesa set or coil or nest of tubes, or

a conduit or passage, of any suitable char-.

acter, to which water to be heated is supplied by a pipe 14 and fromwhich the hot water is carried off by a pipe 15'; and an outer shell,casing or jacket 16 furnishing a conduit or passage for the heatingmedium, such medium being in this case hot water. l cali this anindirect heater in order tc appropriate to it a distinguishing term andto indicate that the water drawn from it for use (which for the purposesof this specification ii call domestic water) is not directly heated bya flame, or auto-generative source of heat, but indirectly by a mediumwhich receives heat primarily from. an autogenerative source anddelivers heat by thermal contact to the domestic-water. For the purposesoat this specification T will distinctively identity the heating mediumjust referred to by the term circulating water.

Water to be heated is supplied to the admis sion pipe 14 of the indirectheater from any source, and here both the receiving and delIVEI'y pipesof the heater are shown as connected to a tank 1?, into which it may beas sumed that cold water is delivered from the service main, and inwhich hot water is stored in the common way.

The shell or outer casing of the heater is connected with a coil orheating unit 1% in the tire space of the furnace, such con nection beingmade by pipes 19 and 20 respectively connecting the upper terminal. ofthe coil 18 with the upper part of the heater shell and the lowerterminal ml the coil with the lower part of said shell, There is also aconnection from the upper part of the heater shell through pipe 23.withthe upper water section of the ihirnace, and a connection 22 fromthe pipe 20 to the lower part of the furnace water leg. In other wordsthe upper and lower parts lillil lib of the heater shell are alsoconnected with the upper and lower parts of the water space of thefurnace. A valve 23 1s lo cated in one of the connections between theheater and furnace, preferably in the lower shaped length of pipe curvedto lie close to the wall of the fire space and having endswhich areattached to connections passing through the water leg and joined to theex ternal connections 19 and 20. The purpose of this coil is obviouslyto bring the cir-- 'culating water into close proximity with the furnacefire so that it will be highly heated even when a slow or dull fire iscarried in the furnace. Other forms of coil having a greater or lesslength or area of heating surface than that here shown may be provided,and said coil may be considered as representativeo'f any sort of watercontainer whatever which is exposed directly to the heat of the fire,but is separated in any way from the Water of the heating system.

This system or mode of heating water for domestic purposes is used onlyat such times and seasons of theyear as require a fire in the furnacefor heating the building, .but at such times the operation is asfollows. Water in the coil or heating section 18 becomes heated by thefire and fiows'through the connection 19 to the top of the heater shell.In the latter it becomes cooled by its thermal contact with the colderwater in the coil or collection of tubes ofthe heater and descends, thenflowing through the connection 20 back to the coil 18, and being againheated. In this way a continuous thermal circulation is set up andmaintained, and the water for domestic purposes is constantly heated. Asthe coil 18 is next to the fire, it receives heat sufficient for thepurpose even in those seasons of mild weather when not much heat isrequired forthe building and the furnace fire is checked to a low ordull condition. in these conditions whatever amount of heat is needed mabe furnished by making the coil 18 Exit great enough length and heatingsur- "ace.

Now a heating element such as the coil 18 which carries enough heatfroma slow fire would receive too much heat when the fire is forced into abrighter or hotter condition in colder weather, and would heat thedomestic water to;too high a temperature, and possibly generate steamwith disastrous effeet, if means were not provided to prevent theseresults. Such means are embodied in the secondary or relief connections21 and 22 between the heater shell orcasing and the water space of thefurnace, and their function is to provide a second circulating pathwhereby the excess heat of the circulating water above that needed toheat the domestic water may be delivered to the heating system. Thecirculating water follows this second path whenever the temperature inthe heater jacket becomes so high that the tendency to downward flowtherein is. less than the tendency to downward flow in the water spaceof the heater between the con-. nections therewith of the pipes 21 and22, as modified by the choke valve 23-. That is, as the water In thefurnace water leg is colder than that in the heating unit 18, a tendencyalways exists for water to flow from the pipe 19 through the pipe 21,into the furnace water space, thence through the circulating when thechoke valve is partly or wholly open both paths are available for theflow of the circulating water,and this water follows one or the other ofthese paths in greater proportion according as the cooling effect on thecirculating water in the indirect heater is more or less intense orrapid. Thus when there is a large demand for domestic hot water and theflow through the tubes of the heater is rapid, or if the temperature ofthe water coming to the heater to be heated is very low, a markedcooling effect takes place on the circulating water in the shell of theheater, and most of the hot circulating water then flows through theheater; but when the domestic water has been heated to a hightemperature so that the cooling effect on the circulating water is lessrapid, and the circulating tendency there acting is less'than that dueto the relatively low temperature of the water in the furnace water leg(which is cooler of the circulating water is delivered into the househeating system and there economically used.

By appropriately adjusting the choke valve 23 the temperature to whichthe domestic water is heated may be correspondingly regulated. Thus itsmaximum temperature This tendency may be may be kept down to that of thewater in the furnace water leg, or it may be caused to mount higher, forby choking the circulating path through'th'e water leg, the path throughthe heater may be made of less resistance, even though the temperaturein the heater is higher than that in the water leg. The location atwhich I have shown the choke valve is that which I prefer on account ofits efficiency and convenience of installation and operation. Thisvalve, however, may be located elsewhere, for instance, in theconnection 21, because a choke valve appliedanywhere to impede flowthrough the second-or relief path will answer the purpose, and likewiseforthis purpose any construction of valve may be used which is adaptedto be set in different more or less open or closed adjustments.structed, or wherever located, the choke valve, or its equivalent, is aregulating means having vthe function and effect of increasing ordiminishing the resistance to flow of the circulating water through thesecondary or relief path, provided for its flow.

The form of installation of the invention hereinbefore described is thatin which the domestic water heater 'is located near the furnace and thesecondary path for the cir-' culatingwater is provided by directconnections with the water space of the furnace. In Figure 4 is shown anarrangement embodying the same principles but differing in the fact thatthe water heater is further removed from the furnace and placed at ahigher level, for example, in the kitchen of a dwelling wherein thefurnace is in the cellar, and that both return paths for the circulatingwater are made through the pipes of the heating system. Here the furnaceis designated 5 and the domestic water heater 13 as before. The storagetank for hot water is'designated 17. 24 represents one of the radiatorsof the heating system connected by a riser 25 and a run 26 with one ofthe uptake pipes 11 of the furnace, and by a riser 27 and run 28 withthe return pipe 12. This view shows also by way of illustration amodified form of heating unit for the circulating water, the same-beinga section 18 of the furnace water leg closed in by webs or partitions 29to make a compartment altogether separate from. the rest of the waterleg. The normal circulation of water between the heating unit and thewater heater is through the pipe 19 to the heater jacket, and fromthelatter throu h the pipe 20 to the return riser 27 of t e radiator,the return run 28, and a branch 30 to the lower connection of theheating unit. The secondary path corresponding tothat provided by thepipes 21' and 22 previously described is provided by a pipe 31 leadingfrom the heater shell to the radiator supply riser 25, and thence by thepiping of However con-' the heating system to the pipe 30 and auxiliaryheating unit 18*. A choke valve 23 in the pipe 31 performs the sameoffice as the choke valve 23. In function and mode ofoperation thesystem last described is equivalent to that first. described.

By the means thus explained it is made possible to use the furnacewhenever a fire, even a 'slow one, is maintained therein, for heatingwater to as high a temperature as is ordinarily needed for domesticpurposes such as bathing, washing household utensils and clothing, andso forth; while at the same time safeguards are provided to avoidoverheating of the domestic Water or of the circulating systemcontaining the water provided for such heating. This invention isadapted for use only in connection with a hot water heating system, butWithin this limitation it may be applied in various ways, other thanthose here shown, to all types of such systems all. of which are withinthe scope of my claim to protection herein.

In the foregoing description I have applied certain identifying terms tothe various parts of the apparatus in order conveniently to-distinguishthese parts from one another in the interest of clarity and brevity ofdescription, but without intending any limitation in the scope of myclaimed protection. These terms are used in the following claims withthe same purpose and intent, and are to be construed accordingly.

culating heating water becomes overheated.

2. The combination of an indirect domestic water heatin apparatuscomprising a water heater having interior conducting means for the waterto be heated and an outer shell for the circulating heating water, aheatin furnace forming the heat generator o a main water heating system,an auxiliary heatin unit in said furnace for the circulating eatinwater, connections between the outlet and inlet of said auxiliaryheating unit and the upper and lower parts of said shell respectively,and a relief connection from the upper part of said shell to arelatively hi her ortion of said heating system, a re ative y lowerportion of .said heating system being connected to said auxiliaryheating unit and thereby providing with said relief connection asecondary path for water flowing through said auxiliary heating unit.

3. Means for heating water forfdomestic use indirectly from the furnaceof a main heating system comprising an indirect heater having separatechannels for the water to be heated and for circulating heating Waterrespectively, an auxiliary heating unit in the furnace havingconnectionswith the channel for circulating heating water, and connecting meansproviding for a 'return flow of said circulating heating water after ithas passed through said indirect.

heating water, and: means connecting said normal circuit and said mainheating system 'and providing a secondary path of flow for saidcirculating heating water after it haspassed through said indirectheater, from said indirect heater into said main heating system underabnormal conditions, whereby excessheat in said circulating heatingwater may be transferred to the mass of water in said main heatingsystem.

5'. The combination with a main hot water heatinosystem and the furnacethereof, of an indirect domestic water heater having conducting meanstherein for the water to be heated and a conduit therein for thecirculating heating water, a heating unit in the furnace, connectionsforming with said auxiliary heating unit and said conduit a normalcircuit r said circulating heatmg water, means connecting said normalcircuit and said main heating system and providing a secondary path offlow for said circulating heating water after it has passed through saidindirect heater, from said indirect heater into said main heating systemunder abnormal conditions, whereby excess heat in said circulatingheating water may be transferred to the mass of, water in said mainheating system, and regulating means to increase or diminish theresistance toflow of the circulating heating water through saidsecondary path.

6. The combination with the furnace of a hot water heating system, of anindirect domestic water heater, a separate heating unit in the furnace,connebtions providin a circulating path for water between sai unit andsaid indirect heater, connecting means providing a secondary or reliefpath for the circulating water after it has passed through said indirectheater, from the indirect heater into the heating system, and means forvarying the resistance to flow through the secondary path. 7. Thecombination with the furnace of a hot water heating system, of anindirect domestic water heater, a separate heating unit in the furnace,connections providing a circulating path for water between said unit andsaid indirect heater, connecting means providing a secondary or reliefpath for the circulatin water after it has passed through said indirectheater, from the indirect heater into the heating system, and a chokevalve in the secondary path adjustable to impede in a greater or lessdegree the flow of circulating water through said secondary path.

8. The combination with the furnace of a hot water heating system, of anindirect domestic water heater, a separate heating unit in the furnace,connections providing a circulatin path for water between said unit andsaid indirect heater, and connecting means providing a secondary orrelief path for the circulating water direct from the circulation spaceof said indirect heater to said main heating system and from said mainheating system into the return path of the circulating heating water.

In testimony whereof I have aflixed my signature.

GHETWOOD SMITH.

